Monday, September 8, 2008

A Practical Approach to Omega Fats

Hunter-gatherers and healthy non-industrial cultures didn't know what omega-6 and omega-3 fats were. They didn't balance nutrients precisely; they stayed healthy by eating foods that they knew were available and nourishing. Therefore, I don't think it's necessary to bean count omega fats, and I don't think there's likely to be a single ideal ratio of n-6 to n-3. However, I do think there's evidence for an optimal range. To find out what it is, let's look at what's been done by healthy cultures in the past:

Hunter-gatherers living mostly on land animals: 2:1 to 4:1

Pacific islanders getting most of their fat from coconut and fish: 1:2

Inuit and other Pacific coast Americans: 1:4 or less

Dairy-based cultures: 1:1 to 2:1

Cultures eating fish and grains: 1:2 or less

It looks like a healthy ratio is between 4:1 and 1:4 n-6 to n-3. Some of these cultures ate a good amount of n-3 polyunsaturated fat, but none of them ate much n-6 [One rare exception is the !Kung. SJG 2011]. There are three basic patterns that I've seen: 1) low fat with low total n-6 and n-3, and a ratio of less than 2:1; 2) high fat with low total n-6 and n-3 and a ratio of 2:1 or less; 3) high fat with low n-6 and high n-3, and a low carbohydrate intake.

I think there's a simple way to interpret all this. Number one, don't eat vegetable oils high in n-6 fats. They are mostly industrial creations that have never supported human health. Number two, find a source of n-3 fats that can approximately balance your n-6 intake. In practical terms, this means minimizing sources of n-6 and eating modest amounts of n-3 to balance it. Some foods are naturally balanced, such as grass-fed dairy and pastured lamb. Others, like coconut oil, have so little n-6 it doesn't take much n-3 to create a proper balance.

Animal sources of n-3 are the best because they provide pre-formed long-chain fats like DHA, which some people have difficulty producing themselves. Flax oil may have some benefits as well. Fish oil and cod liver oil can be a convenient source of n-3; take them in doses of one teaspoon or less. As usual, whole foods are probably better than isolated oils. Weston Price noted that cultures throughout the world went to great lengths to obtain fresh and dried marine foods. Choose shellfish and wild fish that are low on the food chain so they aren't excessively polluted.

I don't think adding gobs of fish oil on top of the standard American diet to correct a poor n-6:n-3 ratio is optimal. It may be better than no fish oil, but it's probably not the best approach. I just read a study, hot off the presses, that examines this very issue in young pigs. Pigs are similar to humans in many ways, including aspects of their fat metabolism. They were fed three diets: a "deficient" diet containing some n-6 but very little n-3; a "contemporary" diet containing a lot of n-6 and some n-3; an "evolutionary" diet containing a modest, balanced amount of n-6 and n-3; and a "supplemented" diet, which is the contemporary diet plus DHA and arachidonic acid (AA).

Using the evolutionary diet as a benchmark, none of the other diets were able to achieve the same fatty acid profile in the young pigs' brains, blood, liver or heart. They also showed that neurons in culture require DHA for proper development, and excess n-6 interferes with the process.

With that said, here are a few graphs of the proportion of n-6 in common foods. These numbers all come from nutrition data. They reflect the percentage n-6 out of the total fat content. First, animal fats:

These range from very low in n-6 to very high. Most of the modern, industrially processed oils are on the right, while most traditional oils are on the left. I don't recommend using anything to the right of olive oil on a regular basis. "HO" sunflower oil is high-oleic, which means it has been bred for a high monounsaturated fat content at the expense of n-6. Here are the meats and eggs:

n-3 eggs are from hens fed flax or seaweed, while the other bar refers to conventional eggs.

A few of these foods are good sources of n-3. At the top of the list is fish oil, followed by n-3 eggs, grass-fed butter, and the fat of grass-fed ruminants. It is possible to keep a good balance without seafood, it just requires keeping n-6 fats to an absolute minimum. It's also possible to overdo n-3 fats. The traditional Inuit, despite their good overall health, did not clot well. They commonly developed nosebleeds that would last for three days, for example. This is thought to be due to the effect of n-3 on blood clotting. But keep in mind that their n-3 intake was so high it would be difficult to achieve today without drinking wine glasses full of fish oil.

32 comments:

Canola/Rapeseed has n-6/n-3 ratio of 2:1 or even better. Why dont you recommend it?. It is useful esp to populations that have poor access to sea food. Fish-oil is ecologically a delicate thing. I have read that fish-eating birds are losing population because they cant get fishes to eat.

Thanks Stephan - a fitting climax to your series on omegas 3 and 6. I think the changes I will make will be to stop taking Flax supplementation (links to prostate cancer mentioned on Mark's Daily Apple also influence this) and to stop using tahini as a condiment. Would you agree that tahini is probably to be avoided? This is basically sesaeme oil, right?

I am well informed of the benefits of higher omega-3 intake and the potential risks involved in the higher intake of omega-6 fatty acids. Still I would like to point out that many of the potential risks involved in the higher linoileic acid (omega-6) intake do not seem to actualize in real life. Recently this was clearly seen in a study published in July in American Journal of Clinical Nutrition. In the study higher intake of linoleic acid (omega-6) intake was associated with reduced total and cardiovascular mortality.

Gyan:Canola oil is high in PUFAs - about 32% - similar to peanut oil. Animal foods usually about 2-16% PUFAs, by calories. Wild caught fish are lean and have less PUFAs than those from farms. A mixed diet of whole animal foods would be a lot lower in PUFAs than a diet of nuts, seeds, and the oils from most plants. Why eat PUFA oils? They usually taste awful, and we don't need any of them. It would be better to eat chicken and turkey with skin to most PUFA oils, IMO. I think the amount of PUFA matters as much as the ratio, or more.

Juhana:I think the modern diet filled with refined sugars and flours does more to cause inflammation than eating a lot of vegetable oils, although I'd avoid all oils with more PUFAs than olive oil (like Stephan suggested). In fact, I use macadamia oil rather than olive oil, because it has only 2% PUFAs and a 6:1 omega-6 ratio or lower, based on what I've read.

http://www.nutritiondata.com/facts/nut-and-seed-products/3123/2

The study showing benefits from n-6 is probably just seeing the benefit from avoiding trans fat. Trans fats (or some other substance in refined hydrogenated oils) cause obesity in animals and block many enzymes from working properly. However, it might not be as bad as the refined carbs, chemicals, and other things in food that contain trans fat.

Stephan:The Inuits also aged rapidly, based on Vilhjalmur Stefansson's reports. He said Eskimo women were sometimes grandmothers before age 23 and they looked as old at 60 as Americans of his time (not eating PUFA oils) did at 80. I disagree that a high ratio of omega-3 to omega-6 is healthy. I think it's best to keep PUFAs lower and not eat a lot of perishable n-3 oils (like fatty fish). I also feel grain-fed meat is not nearly as big a concern as PUFA oils, nuts, seeds and the like. I wager that somebody eating nothing but whole chicken is going to be healthier than somebody eating nuts and seed oils.

Stephan,There is a post over at Mark's Daily Apple about Flaxseed and Mark recommending fish oils. A comment was made that you can get DHA and EPA from algae supplements. Are they as good as fish oils? I don't think the supplements are available everywhere just over the net? Have you heard of them and what are your thoughts?http://www.water4.net/

I can't comment on how much DHA v. EPA is optimal for your body. But recall the mnemonic that the n-3's go in alphabetical order:

ALADHAEPA

Your body can (inefficiently) turn ALA into DHA, and DHA into EPA. So my gut feeling is that having more EPA straight up is beneficial so that your body doesn't have to use its inefficient conversion system to make it.

I'm curious to any good answer about what ratios are optimal, however.

The reason I don't recommend canola oil is complicated. It's fairly high in n-3, which is easily oxidized. So what manufacturers do is hydrogenate it during the refining process to remove some of the n-3 and stabilize it. So refined commercial canola is often hydrogenated and not even very rich in n-3.

You can get unrefined canola oil sometimes, but it's not suitable for cooking due to the n-3. Canola oil is also high in polyunsaturated fat in general, which could be a problem if you eat a lot of it.

Hi Methuselah,

I still use tahini every now and then. You're right that it's mostly sesame oil. I try not to make it a staple, but I do enjoy eating it sometimes.

Juhana,

The study you pointed out is epidemiological, so it can't sort out correlation from cause. The only hard evidence comes from intervention trials where they replaced saturated fat with n-6. As far as I'm aware, in most of these trials total mortality went up or remained the same.

I posted some lifespan data for the Inuit from Stefansson's "Cancer, Disease of Civilization" a while back. They actually had a fairly good lifespan for HGs (43.5 not incl infant mortality), if we can extrapolate from this one group. Some of them were living past 90. The records are from a Russian mission in Alaska that recorded births and deaths.

I don't know whether algae are a good source of n-3. The long-chain fatty acids in fish originally come from algae I believe. However, on principle I'd go with fish oil unless you're totally against eating fish. Simply because humans seem to be designed to get their most important nutrients from animals rather than plants.

I am well aware, that the study type can not establish causality. Still the researchers themselves state (in the full study) that the study type reflects well the actual dietary intake of different fatty acids.

I do not agree that other studies in general would show opposite results. I just refer to the results of the 20 year follow-up of the Nurses' Health Study where higher intake of polyunsaturated fatty acids was clearly associated with reduced CHD mortality. The omega-6 fatty acids were not separated from the omega-3's but as it is well known that the ratio is poor in the American diets, the results show in practise that higher omega-6 intake was beneficial. Higher polyunsaturate (and particularly omega-6 linoleic acid) intake may slightly increase cancer risk but the benefit in cardiovascular mortality risk reduction is so great that the total mortality effect is still likely to be lower.

I will come back later. I have been away for two days at a lipid conference.

A brief thought on the nurses study comment. Thanks Juhana for the post which is thought provoking. I suggest there are to many potentially confounding and related factors to draw any conclusion as to the role of Omega 6 or 3(undifferentiated) (as against related factors such as aspirin hormone intake, mono saturates tied to polyunsaturates eg olive oil 3 etc) in lowering coronary disease risk profiles where associated with higher polyunsaturates intake.

The Nurses' Health study also can't establish causality. You really can't base your views on epidemiological studies when there are intervention trials around. As Robert said, epi studies are full of confounders (which cannot all be adjusted for, despite the investigators' best efforts). If you look at the totality of the intervention trials, they do not support the hypothesis that n-6 PUFA decreases overall mortality. This makes good sense since a high intake of n-6 is not natural for the human body. We've only been eating a lot of it for 50 years or so.

I am well aware of that. But neither can you rely on short term intervention trials only. We need both types of studies to get a full picture.

The Lyon Diet Heart Trial was an intervention trial where butter was replaced with rapeseed oil based margarine (non-transfat). Coronary heart disease events were reduced by impressive 70 percent. The trial included some other dietary changes as well but if margarines and PUFAs were as harmful as many low-carbers state, you could not get that kind of impressive results.

It's a fair point about study length. However, I consider epi studies good for formulating hypotheses only. On a number of occasions, conclusions drawn from epi studies have fallen through when tested in interventions.

I agree that the Lyon trial was an impressive and interesting result. It would be hard to argue that the result was due to increased n-6 intake however, since the intervention group was eating less n-6 than the control group. It was more likely due to an improved n-6:n-3 ratio from the n-3 in the canola oil. Total PUFA probably went down as well, since n-6 went down.

Omega 3 and 6 are two separate families. Each member of each family has distinct and separate properties, and so different uses in the body.

The 18 `mother` Omega 3 and 6 carbons fats linoleic(6)and alpha linolenic (3) acid are plant based. Neither humans nor animals can make them - we both MUST get them from diet.

The longer Omega 3 and 6 fats are found in animals humans and simpler living things.

Humans animals and simpler things can convert the mother fats to longer fats of the same families. To save doing the conversion ourselves we eat the fats animals have already converted, like DHA and EPA in fish.

The mother omega 3 and 6 plant fats are found in low levels in green things, with generally more 3 than 6. They are also found in SEASONAL plant reproductive material in higher quantities generally with varying skews to Omega 6. Nuts and some seeds have very high levels of Omega 6 (see Stephan's graph above). Overall the mother fats would have been available in quite low amounts and around a balance of 1:2 to 2:1 depending on what foods were accessible. The maintenance need for the 18 carbon plant based Omega 6 is likely under 1% of calories. This would suggest the absolute need for the Omega 3 mother fat is similar.

BUT our ancestors did not have disturbed digestion, refined foods, significant alcohol, and a host of factors which can block the conversion of the mother fats to the longer fats, all of which complicate any absolute answer as to optimal intake.

Long chain Omega 3 and 6 would have come form the marine food chain which is biased to omega 3 by a factor of about 10. A shoredweller could have eaten significant amounts of long chain omega 3 in time of marine plenty.

This suggest to me that we need to more or less balance the omega 3 and 6 plant fats but maybe under 6-8 grams a day of Omega 6, and that the limit on marine based long chain Omega 3s (DHA +EPA as a measure) is what you could have reasonable eaten based on a variety of fish, maybe 1-3 combined total grams a day.

The amount of long chain 3 required seems to be a function of the intake of Omega 6 and will again depend on digestion etc.

MEDICAL ADVICE

Please consult with your doctor before making significant alterations to your diet and more so if on blood thinners asprin etc as Omega 3s can cause blood thinning. Also if on `high` amounts of Omega 3 please advise prior to surgery child birth etc. Those who are pregnant or planning pregnancy should also take advice.

Mercury contamination is an issue for some fish - some inland water are polluted - bigger and older fish like tuna carry health warnings as to the amount you should eat - check your government health site.

Good quality fish oils should be distilled which removes mercury, but fish come with lots of nutrients, are a complete package and are the recommendation of those that have spent a lifetime researching in the field. Iodine is needed to control metabolism. Zinc is necessary to fat conversion.......

Omega six is the precursor of all the major inflammatory chemicals. Omega six connects to tissue creation and destruction, new life, immune function etc.

Of course refined food will contribute to the pressure that lead to the formation of inflammatory chemicals but Omega 6 is the primary precursor and the pathway targeted by modern anti inflammatories.

Whole Chicken

Industrial chicken as per Stephan's graph is grain fed and so contains surprising amounts of Omega 6 and very little 3 - so meat is a good source of Omega 6 but unless grass fed will contain little 3.

ED

The order is ALA EPA DHA. The amount of ALA converted to DHA in men can be very small - a fraction of a % in some, due to conversion blockers etc.

Optimal Ratios

There are no definitive answers but the body needs both DHA and EPA as they have distinct and important roles.

SUE

Algal oils.

Better for the environment and a concentrated pure source of DHA and or EPA, but do not carry the same range of fats or other nutrients as whole fish.

How much

No certain answers for the reasons given above but the American Heart Association recommends a gram a day of EPA plus DHA (500mg of each) and an American mental health organisation recommends 2 grams total a day.

Are you familiar with and do you have an opinion on Ray Peat's writings? He's a biologist who thinks consuming any amount of PUFA -n-6 or n-3- is a bad idea. An interesting argument that runs counter to the current mainstream take on n-3.

Omega 3 and 6 are in general terms unique in common fats in that we and animals cannot make them. They are both central to body function. The key questions is what are the optimal intakes of the plant and longer chain Omega 3 and 6s in humans

The brain is about 60% fat dry weight.

Of that approximately 25% is DHA (Omega 3) and 25% AA and AD (Omega 6).

All animals have a similar ratio.

DHA is essential to brain and retinal function. 60% of the retinal fats are DHA. The Oxidation of DHA is likely essential to sight, immune function, cell control, cell death etc...

Omega six AA is essential to vascular structure and function, inflammation, tissue creation and destruction, hormone production etc...

Would we need as much long chain Omega 3 if we were consuming levels of Omega 6 close to 1% of energy - probably - NO.

Trials that look at PUFAs without considering the individual underlying fats are of little use in saying anything much.

The body appears to have developed a range of specific mechanisms to protect against damaging oxidation of DHA, eg protectins and resolvins, hormones with a relationship to DHA like melatonin etc.

Dolphins do very well on a very high long chain Omega 3 diet (eg marine food products) which suggests that high intake of Omega 3 per se is not detrimental.

It is the oxidisation of LA linoleic acid that seems to create the problems. This could happen in the eicosanoid cascades outside the membranes or as a result of oxidation in the mitochondria. As yet there does not seem to be the same Omega 6 oxidation protection mechanisms for Omega 6 that are found for Omega 3.

I suggest it may be the body is not designed to use scarce Omega 6 as fuel, because the body has little experience of Omega 6 being used as fuel.

Pregnancy depletes women of Omega 3s to build babies and their brains. In animals brain size reduction in offspring has been observed in later multiple pregnancies where Omega 3 supply was low.

High availability of DHA is suggested as an explanation for the advantages of the first born.

So complicated but with lots of reading;

Should we reduce Omega 6 plant fat intake - YES

Do women have a higher need for long chain Omega 3s and 6s to make babies - YES

Should we balance the omega 3 and 6 plant fat intake - YES

Can we benefit from moderate intake of aquatic products that have a lot times more long chain 3 than 6 and the essential minerals etc that come in fish -YES

IS the question of supplies of fish a huge question - YES !!!!

Does a ton of farmed carnivorous fish require 4-5 tons of oily fish as feed - from what I read - YES

Are there alternative supply options like algae or the distant possibility of long chain yielding crops? Algal production is already under way. They are looking a genetic manipulation of crops to include long chain PUFAs. The implication of making long Omega 3 and 6 available in the terrestrial environment in plant fats are enormous.

Thanks for your reply. I would love to read a post on your thoughts on Peat's reasoning. I'm certainly not qualified to speak for him, but I think he addresses each of the points you made in the three articles I mentioned. Thanks for this blog, which is required daily reading for me.

I just read his articles more thoroughly. I think he makes a lot of good points, but I disagree with some of it.

Many healthy traditional cultures ate a fair amount of PUFA, mostly n-3. The Inuit ate a lot of it, and the Kitavans eat the equivalent of about 1 tsp per day of fish oil (4g).

To counter the argument that DHA is an important fat in brain function, he cites some cell culture data that cells can divide indefinitely without the 'essential' fatty acids. What cells do in a dish is a far cry from what is optimal in the human brain. As a matter of fact, cell culture data are virtually irrelevant to the question.

He also cites the fact that insects can live without PUFA. Well that's also irrelevant, because they have different biosynthetic pathways than we do.

So he is not able to explain why the brain concentrates DHA and other PUFA.

Robert makes a good point that mothers shunt n-3 fats to their babies to help build their brains. If they weren't important for development, why would that happen?

Hi Stephan- Thanks for the analysis. I agree that neither cell-culture studies nor insect biology should be used to draw conclusions about what happens in the human body. I notice that he also cites a fair number of studies on rats and other mammals, and even humans receiving intravenous feeding, to support various points (including some about brain health/function). These are, I think, worth noting- though of course the animal studies can not be considered surrogates for human studies. As to the brain's affinity for DHA, is it possible that the brain concentrates as much as it needs during development and then no longer requires more (beyond the very small unavoidable amount in a healthy diet) in adulthood? I've seen Chris Masterjohn's work mentioned here. I haven't dropped the $15 for his special report on PUFA, but the abstract states "In... healthy adults (other than women who are seeking to conceive, pregnant, or lactating), however, the requirement (for EFA) is infinitesimal if it exists at all".I agree that the fact that healthy cultures have eaten given amounts of n-3 on a regular basis is good evidence that those amounts of n-3 are, at the least, benign- in the context of those cultures' lifestyles/total environment. I'm just playing devil's advocate. Perhaps I've been eating too much of the devil's fat recently.

I haven't read Chris Masterjohn's PUFA report yet, but I'm sure he backs himself up well. I think there's a difference between how much PUFA is necessary and how much is tolerated. They may be right that we need very little PUFA to avoid deficiency; I haven't looked into that so I can't evaluate it.

I do feel comfortable saying that we can be healthy getting the amount of n-3 that one would get from eating fish regularly. So if n-3 is toxic, it's probably only in large amounts.

Robert: "Dolphins do very well on a very high long chain Omega 3 diet (eg marine food products) which suggests that high intake of Omega 3 per se is not detrimental."

Dolphins also swim in cold water 24 hours a day. How many people do the same? Wild salmon are less than 16% PUFAs by calories. Also, fish is a whole food, unlike taking fish oil, which is usually processed and does not contain protein, water-soluble vitamins, and minerals that a whole fish would contain.

"Industrial chicken as per Stephan's graph is grain fed and so contains surprising amounts of Omega 6 and very little 3 - so meat is a good source of Omega 6 but unless grass fed will contain little 3."

It's still much lower in PUFAs than most nuts, seeds, and vegetable oil products that are used for cooking. As a percent of calories, it's only 13.5% PUFAs (max). Meanwhile, nuts like almonds are over 20% PUFAs. To put things in perspective, eating a half chicken with skin (460g) would give < 15g of PUFAs, while a cup of whole almonds (143g) would give 17g of PUFAs. Most nuts are even worse.

Peter: Ray Peat is not against all foods containing PUFAs. He eats red meat, cheese, milk, shellfish, lean white fish, coconut oil, eggs, etc. He's mainly in favor of a high SFA to PUFA (and MUFA/PUFA) ratio, so they are "diluted" (his words). It is impossible to avoid PUFAs, that is a straw man used by his critics (Mary Enig), but he doesn't say to eliminate PUFAs, only to keep them very low and dilute them with SFAs and MUFAs. He mainly eats red meat, dairy, and coconut fats.

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